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Author |
Malik, Z.; Broadley, S.; Herkelrath, S.J.C.; Newbrook, D.W.; Kemp, L.; Rutt, G.; Gal, Z.A.; Blandy, J.N.; Hadermann, J.; Davies, D.W.; Smyth, R.D.; Scanlon, D.O.; Huang, R.; Clarke, S.J.; Hyett, G. |
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Title |
Observation and enhancement through alkali metal doping of p-type conductivity in the layered oxyselenides Sr₂ZnO₂Cu₂Se₂ and Ba2Zn1-xO2-xCu2Se2 |
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A1 Journal article |
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Year  |
2024 |
Publication |
Journal of materials chemistry C : materials for optical and electronic devices |
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Keywords |
A1 Journal article; Electron microscopy for materials research (EMAT) |
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Abstract |
The optoelectronic properties of two layered copper oxyselenide compounds, with nominal composition Sr2ZnO2Cu2Se2 and Ba2ZnO2Cu2Se2, have been investigated to determine their suitability as p-type conductors. The structure, band gaps and electrical conductivity of pristine and alkali-metal-doped samples have been determined. We find that the strontium-containing compound, Sr2ZnO2Cu2Se2, adopts the expected tetragonal Sr2Mn3SbO2 structure with I4/mmm symmetry, and has a band gap of 2.16 eV, and a room temperature conductivity of 4.8 x 10(-1) S cm(-1). The conductivity of the compound could be increased to 4.2 S cm(-1) when sodium doped to a nominal composition of Na0.1Sr1.9ZnO2Cu2Se2. In contrast, the barium containing material was found to have a small zinc oxide deficiency, with a sample dependent compositional range of Ba2Zn1-xO2-xCu2Se2 where 0.01 < x < 0.06, as determined by single crystal X-ray diffraction and powder neutron diffraction. The barium-containing structure could also be modelled using the tetragonal I4/mmm structure, but significant elongation of the oxygen displacement ellipsoid along the Zn-O bonds in the average structure was observed. This indicated that the oxide ion position was better modelled as a disordered split site with a displacement to change the local zinc coordination from square planar to linear. Electron diffraction data confirmed that the oxide site in Ba2Zn1-xO2-xCu2Se2 does not adopt a long range ordered arrangement, but also that the idealised I4/mmm structure with an unsplit oxide site was not consistent with the extra reflections observed in the electron diffractograms. The band gap and conductivity of Ba2Zn1-xO2-xCu2Se2 were determined to be 2.22 eV and 2.0 x 10(-3) S cm(-1) respectively. The conductivity could be increased to 1.5 x 10(-1) S cm(-1) with potassium doping in K0.1Ba1.9Zn1-xO2-xCu2Se2. Hall measurements confirmed that both materials were p-type conductors with holes as the dominant charge carriers. |
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https://www.webofscience.com/api/gateway?GWVersion=2&SrcApp=brocade2&SrcAuth=WosAPI&KeyUT=WOS:001324 |
Publication Date |
2024-09-19 |
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ISSN |
2050-7526; 2050-7534 |
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Additional Links |
UA library record; WoS full record |
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Impact Factor |
6.4 |
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Open Access |
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Approved |
Most recent IF: 6.4; 2024 IF: 5.256 |
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Call Number |
UA @ admin @ c:irua:209447 |
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9337 |
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